Android example source code file (CacheManager.java)
The CacheManager.java Android example source code/*
* Copyright (C) 2006 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.webkit;
import android.content.Context;
import android.net.http.AndroidHttpClient;
import android.net.http.Headers;
import android.os.FileUtils;
import android.util.Log;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FilenameFilter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.List;
import java.util.Map;
import org.bouncycastle.crypto.Digest;
import org.bouncycastle.crypto.digests.SHA1Digest;
/**
* The class CacheManager provides the persistent cache of content that is
* received over the network. The component handles parsing of HTTP headers and
* utilizes the relevant cache headers to determine if the content should be
* stored and if so, how long it is valid for. Network requests are provided to
* this component and if they can not be resolved by the cache, the HTTP headers
* are attached, as appropriate, to the request for revalidation of content. The
* class also manages the cache size.
*/
public final class CacheManager {
private static final String LOGTAG = "cache";
static final String HEADER_KEY_IFMODIFIEDSINCE = "if-modified-since";
static final String HEADER_KEY_IFNONEMATCH = "if-none-match";
private static final String NO_STORE = "no-store";
private static final String NO_CACHE = "no-cache";
private static final String MAX_AGE = "max-age";
private static final String MANIFEST_MIME = "text/cache-manifest";
private static long CACHE_THRESHOLD = 6 * 1024 * 1024;
private static long CACHE_TRIM_AMOUNT = 2 * 1024 * 1024;
// Limit the maximum cache file size to half of the normal capacity
static long CACHE_MAX_SIZE = (CACHE_THRESHOLD - CACHE_TRIM_AMOUNT) / 2;
private static boolean mDisabled;
// Reference count the enable/disable transaction
private static int mRefCount;
// trimCacheIfNeeded() is called when a page is fully loaded. But JavaScript
// can load the content, e.g. in a slideshow, continuously, so we need to
// trim the cache on a timer base too. endCacheTransaction() is called on a
// timer base. We share the same timer with less frequent update.
private static int mTrimCacheCount = 0;
private static final int TRIM_CACHE_INTERVAL = 5;
private static WebViewDatabase mDataBase;
private static File mBaseDir;
// Flag to clear the cache when the CacheManager is initialized
private static boolean mClearCacheOnInit = false;
/**
* This class represents a resource retrieved from the HTTP cache.
* Instances of this class can be obtained by invoking the
* CacheManager.getCacheFile() method.
*/
public static class CacheResult {
// these fields are saved to the database
int httpStatusCode;
long contentLength;
long expires;
String expiresString;
String localPath;
String lastModified;
String etag;
String mimeType;
String location;
String encoding;
String contentdisposition;
String crossDomain;
// these fields are NOT saved to the database
InputStream inStream;
OutputStream outStream;
File outFile;
public int getHttpStatusCode() {
return httpStatusCode;
}
public long getContentLength() {
return contentLength;
}
public String getLocalPath() {
return localPath;
}
public long getExpires() {
return expires;
}
public String getExpiresString() {
return expiresString;
}
public String getLastModified() {
return lastModified;
}
public String getETag() {
return etag;
}
public String getMimeType() {
return mimeType;
}
public String getLocation() {
return location;
}
public String getEncoding() {
return encoding;
}
public String getContentDisposition() {
return contentdisposition;
}
// For out-of-package access to the underlying streams.
public InputStream getInputStream() {
return inStream;
}
public OutputStream getOutputStream() {
return outStream;
}
// These fields can be set manually.
public void setInputStream(InputStream stream) {
this.inStream = stream;
}
public void setEncoding(String encoding) {
this.encoding = encoding;
}
}
/**
* initialize the CacheManager. WebView should handle this for each process.
*
* @param context The application context.
*/
static void init(Context context) {
mDataBase = WebViewDatabase.getInstance(context.getApplicationContext());
mBaseDir = new File(context.getCacheDir(), "webviewCache");
if (createCacheDirectory() && mClearCacheOnInit) {
removeAllCacheFiles();
mClearCacheOnInit = false;
}
}
/**
* Create the cache directory if it does not already exist.
*
* @return true if the cache directory didn't exist and was created.
*/
static private boolean createCacheDirectory() {
if (!mBaseDir.exists()) {
if(!mBaseDir.mkdirs()) {
Log.w(LOGTAG, "Unable to create webviewCache directory");
return false;
}
FileUtils.setPermissions(
mBaseDir.toString(),
FileUtils.S_IRWXU|FileUtils.S_IRWXG|FileUtils.S_IXOTH,
-1, -1);
// If we did create the directory, we need to flush
// the cache database. The directory could be recreated
// because the system flushed all the data/cache directories
// to free up disk space.
// delete rows in the cache database
WebViewWorker.getHandler().sendEmptyMessage(
WebViewWorker.MSG_CLEAR_CACHE);
return true;
}
return false;
}
/**
* get the base directory of the cache. With localPath of the CacheResult,
* it identifies the cache file.
*
* @return File The base directory of the cache.
*/
public static File getCacheFileBaseDir() {
return mBaseDir;
}
/**
* set the flag to control whether cache is enabled or disabled
*
* @param disabled true to disable the cache
*/
static void setCacheDisabled(boolean disabled) {
if (disabled == mDisabled) {
return;
}
mDisabled = disabled;
if (mDisabled) {
removeAllCacheFiles();
}
}
/**
* get the state of the current cache, enabled or disabled
*
* @return return if it is disabled
*/
public static boolean cacheDisabled() {
return mDisabled;
}
// only called from WebViewWorkerThread
// make sure to call enableTransaction/disableTransaction in pair
static boolean enableTransaction() {
if (++mRefCount == 1) {
mDataBase.startCacheTransaction();
return true;
}
return false;
}
// only called from WebViewWorkerThread
// make sure to call enableTransaction/disableTransaction in pair
static boolean disableTransaction() {
if (--mRefCount == 0) {
mDataBase.endCacheTransaction();
return true;
}
return false;
}
// only called from WebViewWorkerThread
// make sure to call startTransaction/endTransaction in pair
static boolean startTransaction() {
return mDataBase.startCacheTransaction();
}
// only called from WebViewWorkerThread
// make sure to call startTransaction/endTransaction in pair
static boolean endTransaction() {
boolean ret = mDataBase.endCacheTransaction();
if (++mTrimCacheCount >= TRIM_CACHE_INTERVAL) {
mTrimCacheCount = 0;
trimCacheIfNeeded();
}
return ret;
}
// only called from WebCore Thread
// make sure to call startCacheTransaction/endCacheTransaction in pair
/**
* @deprecated
*/
@Deprecated
public static boolean startCacheTransaction() {
return false;
}
// only called from WebCore Thread
// make sure to call startCacheTransaction/endCacheTransaction in pair
/**
* @deprecated
*/
@Deprecated
public static boolean endCacheTransaction() {
return false;
}
/**
* Given a url, returns the CacheResult if exists. Otherwise returns null.
* If headers are provided and a cache needs validation,
* HEADER_KEY_IFNONEMATCH or HEADER_KEY_IFMODIFIEDSINCE will be set in the
* cached headers.
*
* @return the CacheResult for a given url
*/
public static CacheResult getCacheFile(String url,
Map<String, String> headers) {
return getCacheFile(url, 0, headers);
}
static CacheResult getCacheFile(String url, long postIdentifier,
Map<String, String> headers) {
if (mDisabled) {
return null;
}
String databaseKey = getDatabaseKey(url, postIdentifier);
CacheResult result = mDataBase.getCache(databaseKey);
if (result != null) {
if (result.contentLength == 0) {
if (!checkCacheRedirect(result.httpStatusCode)) {
// this should not happen. If it does, remove it.
mDataBase.removeCache(databaseKey);
return null;
}
} else {
File src = new File(mBaseDir, result.localPath);
try {
// open here so that even the file is deleted, the content
// is still readable by the caller until close() is called
result.inStream = new FileInputStream(src);
} catch (FileNotFoundException e) {
// the files in the cache directory can be removed by the
// system. If it is gone, clean up the database
mDataBase.removeCache(databaseKey);
return null;
}
}
} else {
return null;
}
// null headers request coming from CACHE_MODE_CACHE_ONLY
// which implies that it needs cache even it is expired.
// negative expires means time in the far future.
if (headers != null && result.expires >= 0
&& result.expires <= System.currentTimeMillis()) {
if (result.lastModified == null && result.etag == null) {
return null;
}
// return HEADER_KEY_IFNONEMATCH or HEADER_KEY_IFMODIFIEDSINCE
// for requesting validation
if (result.etag != null) {
headers.put(HEADER_KEY_IFNONEMATCH, result.etag);
}
if (result.lastModified != null) {
headers.put(HEADER_KEY_IFMODIFIEDSINCE, result.lastModified);
}
}
if (DebugFlags.CACHE_MANAGER) {
Log.v(LOGTAG, "getCacheFile for url " + url);
}
return result;
}
/**
* Given a url and its full headers, returns CacheResult if a local cache
* can be stored. Otherwise returns null. The mimetype is passed in so that
* the function can use the mimetype that will be passed to WebCore which
* could be different from the mimetype defined in the headers.
* forceCache is for out-of-package callers to force creation of a
* CacheResult, and is used to supply surrogate responses for URL
* interception.
* @return CacheResult for a given url
* @hide - hide createCacheFile since it has a parameter of type headers, which is
* in a hidden package.
*/
public static CacheResult createCacheFile(String url, int statusCode,
Headers headers, String mimeType, boolean forceCache) {
return createCacheFile(url, statusCode, headers, mimeType, 0,
forceCache);
}
static CacheResult createCacheFile(String url, int statusCode,
Headers headers, String mimeType, long postIdentifier,
boolean forceCache) {
if (!forceCache && mDisabled) {
return null;
}
String databaseKey = getDatabaseKey(url, postIdentifier);
// according to the rfc 2616, the 303 response MUST NOT be cached.
if (statusCode == 303) {
// remove the saved cache if there is any
mDataBase.removeCache(databaseKey);
return null;
}
// like the other browsers, do not cache redirects containing a cookie
// header.
if (checkCacheRedirect(statusCode) && !headers.getSetCookie().isEmpty()) {
// remove the saved cache if there is any
mDataBase.removeCache(databaseKey);
return null;
}
CacheResult ret = parseHeaders(statusCode, headers, mimeType);
if (ret == null) {
// this should only happen if the headers has "no-store" in the
// cache-control. remove the saved cache if there is any
mDataBase.removeCache(databaseKey);
} else {
setupFiles(databaseKey, ret);
try {
ret.outStream = new FileOutputStream(ret.outFile);
} catch (FileNotFoundException e) {
// This can happen with the system did a purge and our
// subdirectory has gone, so lets try to create it again
if (createCacheDirectory()) {
try {
ret.outStream = new FileOutputStream(ret.outFile);
} catch (FileNotFoundException e2) {
// We failed to create the file again, so there
// is something else wrong. Return null.
return null;
}
} else {
// Failed to create cache directory
return null;
}
}
ret.mimeType = mimeType;
}
return ret;
}
/**
* Save the info of a cache file for a given url to the CacheMap so that it
* can be reused later
*/
public static void saveCacheFile(String url, CacheResult cacheRet) {
saveCacheFile(url, 0, cacheRet);
}
static void saveCacheFile(String url, long postIdentifier,
CacheResult cacheRet) {
try {
cacheRet.outStream.close();
} catch (IOException e) {
return;
}
if (!cacheRet.outFile.exists()) {
// the file in the cache directory can be removed by the system
return;
}
boolean redirect = checkCacheRedirect(cacheRet.httpStatusCode);
if (redirect) {
// location is in database, no need to keep the file
cacheRet.contentLength = 0;
cacheRet.localPath = "";
}
if ((redirect || cacheRet.contentLength == 0)
&& !cacheRet.outFile.delete()) {
Log.e(LOGTAG, cacheRet.outFile.getPath() + " delete failed.");
}
if (cacheRet.contentLength == 0) {
return;
}
mDataBase.addCache(getDatabaseKey(url, postIdentifier), cacheRet);
if (DebugFlags.CACHE_MANAGER) {
Log.v(LOGTAG, "saveCacheFile for url " + url);
}
}
static boolean cleanupCacheFile(CacheResult cacheRet) {
try {
cacheRet.outStream.close();
} catch (IOException e) {
return false;
}
return cacheRet.outFile.delete();
}
/**
* remove all cache files
*
* @return true if it succeeds
*/
static boolean removeAllCacheFiles() {
// Note, this is called before init() when the database is
// created or upgraded.
if (mBaseDir == null) {
// Init() has not been called yet, so just flag that
// we need to clear the cache when init() is called.
mClearCacheOnInit = true;
return true;
}
// delete rows in the cache database
WebViewWorker.getHandler().sendEmptyMessage(
WebViewWorker.MSG_CLEAR_CACHE);
// delete cache files in a separate thread to not block UI.
final Runnable clearCache = new Runnable() {
public void run() {
// delete all cache files
try {
String[] files = mBaseDir.list();
// if mBaseDir doesn't exist, files can be null.
if (files != null) {
for (int i = 0; i < files.length; i++) {
File f = new File(mBaseDir, files[i]);
if (!f.delete()) {
Log.e(LOGTAG, f.getPath() + " delete failed.");
}
}
}
} catch (SecurityException e) {
// Ignore SecurityExceptions.
}
}
};
new Thread(clearCache).start();
return true;
}
/**
* Return true if the cache is empty.
*/
static boolean cacheEmpty() {
return mDataBase.hasCache();
}
static void trimCacheIfNeeded() {
if (mDataBase.getCacheTotalSize() > CACHE_THRESHOLD) {
List<String> pathList = mDataBase.trimCache(CACHE_TRIM_AMOUNT);
int size = pathList.size();
for (int i = 0; i < size; i++) {
File f = new File(mBaseDir, pathList.get(i));
if (!f.delete()) {
Log.e(LOGTAG, f.getPath() + " delete failed.");
}
}
// remove the unreferenced files in the cache directory
final List<String> fileList = mDataBase.getAllCacheFileNames();
if (fileList == null) return;
String[] toDelete = mBaseDir.list(new FilenameFilter() {
public boolean accept(File dir, String filename) {
if (fileList.contains(filename)) {
return false;
} else {
return true;
}
}
});
if (toDelete == null) return;
size = toDelete.length;
for (int i = 0; i < size; i++) {
File f = new File(mBaseDir, toDelete[i]);
if (!f.delete()) {
Log.e(LOGTAG, f.getPath() + " delete failed.");
}
}
}
}
static void clearCache() {
// delete database
mDataBase.clearCache();
}
private static boolean checkCacheRedirect(int statusCode) {
if (statusCode == 301 || statusCode == 302 || statusCode == 307) {
// as 303 can't be cached, we do not return true
return true;
} else {
return false;
}
}
private static String getDatabaseKey(String url, long postIdentifier) {
if (postIdentifier == 0) return url;
return postIdentifier + url;
}
@SuppressWarnings("deprecation")
private static void setupFiles(String url, CacheResult cacheRet) {
if (true) {
// Note: SHA1 is much stronger hash. But the cost of setupFiles() is
// 3.2% cpu time for a fresh load of nytimes.com. While a simple
// String.hashCode() is only 0.6%. If adding the collision resolving
// to String.hashCode(), it makes the cpu time to be 1.6% for a
// fresh load, but 5.3% for the worst case where all the files
// already exist in the file system, but database is gone. So it
// needs to resolve collision for every file at least once.
int hashCode = url.hashCode();
StringBuffer ret = new StringBuffer(8);
appendAsHex(hashCode, ret);
String path = ret.toString();
File file = new File(mBaseDir, path);
if (true) {
boolean checkOldPath = true;
// Check hash collision. If the hash file doesn't exist, just
// continue. There is a chance that the old cache file is not
// same as the hash file. As mDataBase.getCache() is more
// expansive than "leak" a file until clear cache, don't bother.
// If the hash file exists, make sure that it is same as the
// cache file. If it is not, resolve the collision.
while (file.exists()) {
if (checkOldPath) {
CacheResult oldResult = mDataBase.getCache(url);
if (oldResult != null && oldResult.contentLength > 0) {
if (path.equals(oldResult.localPath)) {
path = oldResult.localPath;
} else {
path = oldResult.localPath;
file = new File(mBaseDir, path);
}
break;
}
checkOldPath = false;
}
ret = new StringBuffer(8);
appendAsHex(++hashCode, ret);
path = ret.toString();
file = new File(mBaseDir, path);
}
}
cacheRet.localPath = path;
cacheRet.outFile = file;
} else {
// get hash in byte[]
Digest digest = new SHA1Digest();
int digestLen = digest.getDigestSize();
byte[] hash = new byte[digestLen];
int urlLen = url.length();
byte[] data = new byte[urlLen];
url.getBytes(0, urlLen, data, 0);
digest.update(data, 0, urlLen);
digest.doFinal(hash, 0);
// convert byte[] to hex String
StringBuffer result = new StringBuffer(2 * digestLen);
for (int i = 0; i < digestLen; i = i + 4) {
int h = (0x00ff & hash[i]) << 24 | (0x00ff & hash[i + 1]) << 16
| (0x00ff & hash[i + 2]) << 8 | (0x00ff & hash[i + 3]);
appendAsHex(h, result);
}
cacheRet.localPath = result.toString();
cacheRet.outFile = new File(mBaseDir, cacheRet.localPath);
}
}
private static void appendAsHex(int i, StringBuffer ret) {
String hex = Integer.toHexString(i);
switch (hex.length()) {
case 1:
ret.append("0000000");
break;
case 2:
ret.append("000000");
break;
case 3:
ret.append("00000");
break;
case 4:
ret.append("0000");
break;
case 5:
ret.append("000");
break;
case 6:
ret.append("00");
break;
case 7:
ret.append("0");
break;
}
ret.append(hex);
}
private static CacheResult parseHeaders(int statusCode, Headers headers,
String mimeType) {
// if the contentLength is already larger than CACHE_MAX_SIZE, skip it
if (headers.getContentLength() > CACHE_MAX_SIZE) return null;
// The HTML 5 spec, section 6.9.4, step 7.3 of the application cache
// process states that HTTP caching rules are ignored for the
// purposes of the application cache download process.
// At this point we can't tell that if a file is part of this process,
// except for the manifest, which has its own mimeType.
// TODO: work out a way to distinguish all responses that are part of
// the application download process and skip them.
if (MANIFEST_MIME.equals(mimeType)) return null;
// TODO: if authenticated or secure, return null
CacheResult ret = new CacheResult();
ret.httpStatusCode = statusCode;
String location = headers.getLocation();
if (location != null) ret.location = location;
ret.expires = -1;
ret.expiresString = headers.getExpires();
if (ret.expiresString != null) {
try {
ret.expires = AndroidHttpClient.parseDate(ret.expiresString);
} catch (IllegalArgumentException ex) {
// Take care of the special "-1" and "0" cases
if ("-1".equals(ret.expiresString)
|| "0".equals(ret.expiresString)) {
// make it expired, but can be used for history navigation
ret.expires = 0;
} else {
Log.e(LOGTAG, "illegal expires: " + ret.expiresString);
}
}
}
String contentDisposition = headers.getContentDisposition();
if (contentDisposition != null) {
ret.contentdisposition = contentDisposition;
}
String crossDomain = headers.getXPermittedCrossDomainPolicies();
if (crossDomain != null) {
ret.crossDomain = crossDomain;
}
// lastModified and etag may be set back to http header. So they can't
// be empty string.
String lastModified = headers.getLastModified();
if (lastModified != null && lastModified.length() > 0) {
ret.lastModified = lastModified;
}
String etag = headers.getEtag();
if (etag != null && etag.length() > 0) ret.etag = etag;
String cacheControl = headers.getCacheControl();
if (cacheControl != null) {
String[] controls = cacheControl.toLowerCase().split("[ ,;]");
for (int i = 0; i < controls.length; i++) {
if (NO_STORE.equals(controls[i])) {
return null;
}
// According to the spec, 'no-cache' means that the content
// must be re-validated on every load. It does not mean that
// the content can not be cached. set to expire 0 means it
// can only be used in CACHE_MODE_CACHE_ONLY case
if (NO_CACHE.equals(controls[i])) {
ret.expires = 0;
} else if (controls[i].startsWith(MAX_AGE)) {
int separator = controls[i].indexOf('=');
if (separator < 0) {
separator = controls[i].indexOf(':');
}
if (separator > 0) {
String s = controls[i].substring(separator + 1);
try {
long sec = Long.parseLong(s);
if (sec >= 0) {
ret.expires = System.currentTimeMillis() + 1000
* sec;
}
} catch (NumberFormatException ex) {
if ("1d".equals(s)) {
// Take care of the special "1d" case
ret.expires = System.currentTimeMillis() + 86400000; // 24*60*60*1000
} else {
Log.e(LOGTAG, "exception in parseHeaders for "
+ "max-age:"
+ controls[i].substring(separator + 1));
ret.expires = 0;
}
}
}
}
}
}
// According to RFC 2616 section 14.32:
// HTTP/1.1 caches SHOULD treat "Pragma: no-cache" as if the
// client had sent "Cache-Control: no-cache"
if (NO_CACHE.equals(headers.getPragma())) {
ret.expires = 0;
}
// According to RFC 2616 section 13.2.4, if an expiration has not been
// explicitly defined a heuristic to set an expiration may be used.
if (ret.expires == -1) {
if (ret.httpStatusCode == 301) {
// If it is a permanent redirect, and it did not have an
// explicit cache directive, then it never expires
ret.expires = Long.MAX_VALUE;
} else if (ret.httpStatusCode == 302 || ret.httpStatusCode == 307) {
// If it is temporary redirect, expires
ret.expires = 0;
} else if (ret.lastModified == null) {
// When we have no last-modified, then expire the content with
// in 24hrs as, according to the RFC, longer time requires a
// warning 113 to be added to the response.
// Only add the default expiration for non-html markup. Some
// sites like news.google.com have no cache directives.
if (!mimeType.startsWith("text/html")) {
ret.expires = System.currentTimeMillis() + 86400000; // 24*60*60*1000
} else {
// Setting a expires as zero will cache the result for
// forward/back nav.
ret.expires = 0;
}
} else {
// If we have a last-modified value, we could use it to set the
// expiration. Suggestion from RFC is 10% of time since
// last-modified. As we are on mobile, loads are expensive,
// increasing this to 20%.
// 24 * 60 * 60 * 1000
long lastmod = System.currentTimeMillis() + 86400000;
try {
lastmod = AndroidHttpClient.parseDate(ret.lastModified);
} catch (IllegalArgumentException ex) {
Log.e(LOGTAG, "illegal lastModified: " + ret.lastModified);
}
long difference = System.currentTimeMillis() - lastmod;
if (difference > 0) {
ret.expires = System.currentTimeMillis() + difference / 5;
} else {
// last modified is in the future, expire the content
// on the last modified
ret.expires = lastmod;
}
}
}
return ret;
}
}
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